Geological traces

In certainly is no easy task to retrace all the sea level variations that have happened in thousands of years. Several different geological techniques which focus on studying specific areas near the coastlines have been used to trace these variations.
The sea digs a horizontal crevice at water level at the base of a cliff which becomes deeper as time goes by. When the sea level decreases, it makes a new etching. Sea level variations can be discovered by measuring the height difference between these two marks
Speleothem: if near the sea there is a cave with stalactites, one can discover sea level variations by studying these stalactites. When the sea level is below the cave the stalactite grows because the water that seeps into the cave causes calcium carbonate to deposit, whereas its formation stops when the sea invades the cave but some organisms carry on with the stalactite’s concretion. These animals which are called serpulides have a calcium carbonate outer shell which therefore can be given an age with the radiocarbon technique and thus enable us to discover when the sea came into contact with the stalactite
When the sea level rises and encounters a specific land conformation it will form a very shallow inland lagoon called “paleolagoon”. This lagoon is where sediment and fossil shells will deposit. Then when the sea level diminishes, one will find organic deposits at different heights on the hills. The age of these deposits is analyzed in order to find out when the sea was at that specific level
When the sea level rises and meets a shelf made of soft rock which is easily eroded, it creates a terrace shaped platform known as “marine terrace” and a sort of slope. At the flex point between the abrasion platform and the beginning of the slope, a place called the “inner edge”, one can measure the sea level of the past.

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